Rotatable abrasive wheels formed of abrasive granules dispersed in and bonded to an organic polymeric matrix formed of a solid or foamed organic polymer or a nonwoven fiber web are well known and widely used. These wheels find utility in deburring and finishing articles such as cast, drilled or punched parts and the like. Burrs and flashing from such parts must be removed to produce a desired shape or surface finish. Small diameter wheels operating at high speeds and high pressures are especially useful. To meet the performance requirements, the wheels or discs must have sufficient strength, be durable and not collapse when subjected to high use pressure against the workpiece or part and not smear.
Examples of abrasive products including a matrix of solid or foamed organic polymer are disclosed by Upton U.S. Pat. No. 2,885,276. Examples of products which contain a matrix formed of a lofty, low density nonwoven web are disclosed by Hoover et al U.S. Pat. No. 2,958,593 and Fitzer U.S. Pat. No. 4,227,350, both assigned to the assignee of the present application.
Polymeric resinous binders used to secure the abrasive granules within the matrix of such products have generally been either of the hard thermosetting type or the strong, tough elastomeric type. Hard thermosetting resins, such as base catalyzed phenol formaldehyde, are widely used to secure abrasive granules to sheet-like backings or to the fibers of a nonwoven web matrix. Such hard resin binders, while usually having high tensile strength, low elongation at break or failure, and resistance to significant change when subjected to elevated temperatures, are undesirably susceptible to brittle fracture. Strong, tough elastomeric resin binders, examples of which are disclosed by Fitzer U.S. Pat. No. 4,227,350, are more desirable in certain applications which require tougher, more durable abrasive products. Such elastomeric binders have excellent tensile strength, a very high elongation at break, and resistance to brittle fracture but, unfortunately, they show significant softening at elevated temperatures as might be encountered when abrasive products are urged against a workpiece at high speeds and pressures. Such softening often results in the undesirable smearing or transfer of portions of the abrasive article to the surface of the workpiece.